Expansible reamer



Aug. 22, 1939.

J. GRANT EXPANS I BLE BEAMER Original Filed Oct. 11, 1937 Cil Patented Aug. 22, 1939 UNI-TED STATES vPATENT OFFICE Application October 11, 1937, Serial No. 168,334 Renewed November 8, 1938 11 Claims.

This invention relates broadly'to the art of reaming well bores and is more particularly directed to certain improvements in apparatus of the general character disclosed in my prior apl plication Serial No. 149,661, filed June 22, 1937, wherein there is shown a normally collapsed reamer adapted to be incorporated in a rotary drill string above a drilling bit, with said reamer having a flow passage entraining circulation fluid under pressure to said bit and being so arranged as to be hydraulically expanded through the medium of a tubular go-devil sent down the drill string by the operator and functioning to restrict the flow of circulation fluid and be translated by the power incident to such restriction to expand the reamer.

The present invention contemplates a more forceful and morepositive expansion of the reamer than can be had with a go-devil which merely restricts the reamer flow passage-and to this end it is an object of the invention to provide `an expansible reamer of the hydraulic'type which includes an actuating go-devil which, when in reamer expandingposition,completely closes the.

strength as to be readily ruptured by a prede-V termined' excess pressure after ther goedevil` reaches the end of its'reamer expanding stroke, so as to estab-lish a restricted circulation flow tending to maintain the reamer in expanded condition.

Another object is to provide a gol-devil in' which the thickness and strength and hence the fracture value of the closing partition may be varied to meet varying requirements andto this end it is formed as a removable fracture plate or blow-out disc' which may be readily renewed or replaced by others havingY greater or less fracture values.

A further object is tofprovideV a reamer of this nature which may be associated ini the drill string with a rat-hole enlarging bit provided with circulationVv jets and functioning to enlarge a rathole while the reamer is collapsed, and which may' subsequently be expanded by a closure godevil of such length that, when in reamer expanding position, it will extend. upwardly into the circulation bore ofthe enlarging bit' to a point above its circulation jets so as to fully close said bore above its highest point of discharge and thus be subjected to the full power of the circulation uid column.

Various other objects and advantages willbe more fully apparent from the following description of the accompanying drawing which forms a part of this disclosure, and which illustrates a preferred form of embodimentV of the invention.

Of the drawing:

Fig. 1 is a vertical sectionV showing a reamer embodying the principles of the present invention, in normal collapsed condition.

Fig. 2 is a similar section showing the go-devil in place and the reamer in its expanded condition.

Fig. 3 is a transverse section taken on the line 3 3 of Fig. l.

Fig, 4 is a vertical section through a lower portion of a well bore and through a portion of a drill string which includes a reamer in a rat-hole seat reaming position and a rat-hole enlarging bit disposed above said reamer, together with an elongated type of go-devil extending upwardly to close the bore of said bit above the circulation jets or discharge orices of the bit to fully shut off the circulation at this point so that the godevil will be subjected to the full power of the circulation column.

Referring to Fig; 1 which shows the reamer in its normal collapsed condition; 20 designates a tubular body having a lower end screw-threaded to connect with a lower sub 2 lto which a suitable pilot or rat-hole bit I2 is connected by the usual pin and box-connection, and an upper end similarly screw-threaded to connect with an upper sub 22 to which a unit of the drill string is con,- nected, also by the usual pin andboX connection.

The bore of the body 2U has a medial portion of relatively small diameter and is enlarged at opposite ends to provide an upper cylinder or mandrel chamber 24 and a lower cylinder or spring chamber 25. A cutter expanding assembly comprises a mandrel head 26- disposed within the mandrel chamber 24, a mandrel bushing 2l disposed within the spring chamber 25, and a connecting mandrel tube 28Hslidable through the medial portion of the bore and connecting the mandrel head and bushing so that they slide within the body bore as a unit. A coil spring 29 within the spring chamber 25 rests upon the lower sub 2| with its upper end bearingl against theY mandrel bushing 2l. 'Ihis spring yieldingly maintains the mandrel assembly in its uppermost positionwith its bushing 2T COIltaCting the stop abutment 36 formed by the upper wall of the spring chamber 25. The cylindrical mandrel head 26 has a downwardly and inwardly converging tapered portion 3l and a closely adjacent end which tapers downwardly and inwardly at a more abrupt angle to form a cutter expanding shoulder 32.

The specific reamer illustrated is one which is particularly effective as a rat-hole seat reamer and for this purpose is provided with three circularly spaced reaming cutters 35i, and although it will be evident that a greater or less number of cutters' may be employed and that cutters of other forms may be used to meet different reaming requirements, it is preferable in a rat-hole seat reamer to provide three reaming cutters of the blade type illustrated. These cutters are dis- Y posed within companion slots formed in the wall of the body 20 to intersect the bore thereof and each cutter is pivoted at Yits lower end on a transverse pin 34 and has secured to itsI lower inner wall portion a leaf spring 35 which extends part way around the pivotal center of the cutter blade with its free end engaging the lower wall of the cutter slot so as to urge the cutter towards collapsed position. The upper inner end portion of each cutter blade is beveled to normally engage the angled shoulder 32 of the mandrel head 25,

. so that upon downward translation of the mandrel assembly the upper ends of the several cutters will be forced outwardly, the reamer being thus expanded, as shown in Fig. 3.

To prevent escape of circulation fluid the man- Y drel assembly is provided with suitable packing rings 38 and 39, this assembly constituting a cutter expanding piston of which the mandrel head 26 functions as an upper piston slidable in the upper chamber or cylinder 24 while the mandrel bushing 21 functions as a lower piston slidable in the lower spring chamber or cylinder .25, these two pistons being joined together by the mandrel tube 28 which serves as a hollow piston rod.

The mandrel head 26 is provided with one or more stoplugs: 44 projecting inwardly into its bore and disposed near the upper end thereof. These stop lugs may be formed integral with the mandrel head or may be formed on a renewable tubular unit 43, as shown in the drawing.

In use,.the collapsed reamer is incorporated in a rotary drill string and during the drilling of the well bore and until such time as it is desired to expand the reamer for a reaming operation, circulation fluid under pressure will flow through the reamer ow passage and to the drilling bit l2. Since the mandrel head 26 and mandrel bushing 21, which function as upper and lower piston elements', have approximately equal areas exposed to the pressure of the circulation fluid, the mandrel assembly will normally be substantially counterbalanced as to fluid pressures and the coil spring 29 will support said mandrel assembly in its elevated position.

This reamer is adapted to be expanded by a go-devil means sent down the drill string by the operator at the well surface, and adapted to engage the mandrel assembly and then be driven downwardly by the circulation fluid pressure to translate said mandrel assembly and thus expand the reamer.

As shown and described in my prior application, above identified, the go-devil previously employed was: of the open bore type and functioned merely to restrict the reamer flow passage so thatthe power available to expand the reamer was only that incident to such flow restriction.

In order to provide a more forceful and positive expansion of the reamer, the present invention includes an improved type of go-devil 59 which, while in some respects similar to the godevil disclosed in my said prior application, is normally provided with a partition or fracture plate 5| disposed in its restricted bore to enable the go-devil, when in reamer expanding position, to entirely close the reamer flow passage and thus be subjected to the full driving power of the cir-V culation fluid pressure. This partition plate is of such thickness and strength as to withstand the pressure required to translate the go-devil in a reamer expanding operation and then to fracture upon being subjected to a predetermined excess pressure, and in the preferred construction the gol-devil is formed of two similar sections detachably joined together by a screw-thread joint 52 permitting separation of the two sections so that the fracture plate or blow-out disc 5l may be renewed or replaced by others having greater or less fracture values. To permit the go-devil to be sent down the drill pipe either end first, its end portions are of duplicate form and are provided with transverse ports 53 and with packing rings 513 serving to prevent leakage of fluid past the go-devil.

When it is desired to expand the reamer in the well bo-re, the operator will send the go-devil 5G down the drill string to engage against the stop lugs 44 of the mandrel assembly and close the reamer flow passage. Since, in a static fluid column, it would require considerable time for the gol-devil to reach the reamer, particularly in a long drill string, it will be advantageous to connect the drill string with the pump at the well surface immediately after the go-devil is started down the drill string and to start the pump to establish circulation so that the downwardly moving fluid column may assist the go-devil in promptly reaching vthe reamer. With the godevil in engagement with the mandrel assembly to completely close the reamer flow passage the circulation fluid pressure will drive the go-devil and mandrel assembly downwardly to expand the reamer, as shown in Fig. 2, and in order to then reestablish circulation of the fluid through the reamer the pressure will be raised to a degree sufficient to rupture the fracture or blow-out plate 5l. When, this occurs the circulation fluid will flow through the restricted bore of the godevil and into the relatively larger mandrel tube 28 and since the lower transverse ports 53 of the go-devil at this time communicate with the mandrel chamber above said mandrel the fluid pressure will exert its predominating pressure upon the top surface of the mandrel head 25 to maintain the reamer in its expanded condition.

In Fig. 4 there is shown anarrangement which may be employed when it is desired to rat-hole ahead as the drilling progresses and then to seatream the rat-hole when a formation justifying a formation test is reached. A drill string suitable for this purpose will include a rat-hole enlarging bit 60 positioned above the normally collapsed seat reamer and provided with suitable ports 6I to direct circulation fluid against the bit rollers or cutters. It will be evident that if a go-devil of the length of one shown in Fig. 2 were used in the arrangement shown in Fig. 4, it would not close off the normally open discharge ports 6| of the enlarging bit 6U and that the continued discharge through these parts would in that sov of such thickness and strength as to withstand instance reduce the power applied to the gol-devil to a degree insufficient to expand the reamer. Therefore in the arrangement shown in Fig. 4 there is provided a relatively long go-devil 50a which, when in reamer expanding position, extends into the axial bore of the .enlarging bit 60 to a point above the ports 6| so as to fully close the flow `passage above its highest point of normal discharge and thus be subjected to the full power of the circulation fluid column during a reamer expanding operation. This elongated go-devil is provided with additional packing rings 55 further insuring against leakage, the upper of which has :particular utility in preventing leakage through the upper transverse ports 53, down along the outer surface of the go-devil and out the discharge ports` 6l of the enlarging bit. In Fig. 4 `the fracture plate 5I is shown in a ruptured condition, and the reamer is illustrated as reaming a rat-hole seat, in which use the rat-hole is first drilled, the drill string being then raised to bring the reamer above the rat-hole shoulder where it will be expanded preparatory to the seat reaming operation. For a more detailed description of formation testing and the use of the reamer in forming a seated rat-hole, reference may be had to my prior application above referred to.

While the drawing shows a reamer particularly adapted for use as a rat-hole seat reamer and while this specification describes its use for such purpose, it will be readily apparent to those skilled in the art of well drilling that the principles herein disclosed are adaptable for incorporation in other structures intended for the same or for other reaming operations, therefore it is to be understood that the invention is not to be restricted in this regard for it is susceptible of embodiment in various other forms within the scope of the claims which follow.

I claim:

1. In an expansible reamer, the combination of; a tubular body adapted to be disposed above a drilling bit to constitute a portion of a rotary drill string conveying circulation fluid under pressure to said bit; a reaming cutter carried by said body, normally in collapsed position; a cutter expanding assembly slidable in said body and having a fluid passage; .and a go-devil having a longitudinal bore normally closed by a partition therein and adapted to be sent down the drill string to engage said assembly and close its fluid passage so as to be subjected to the full power of the circulation uid pressure and be translated thereby to move said assembly to cutter expanding position, said partition being capable of withstanding the pressure required to expand the reamer and adapted to thereafter be fractured by a predetermined excess pressure to reestablish circulation through the expanded reamer.

2. In an expansible reamer, the combination of: a tubular body adapted to be disposed above a drilling bit to constitute la portion of a rotary drill string conveying circulation fluid under pressure to said bit; a reaming cutter carried by said body, normally in collapsed position; a cutter expanding assembly slidable in said body and having a fluid passage; and a go-devil having a longitudinal bore normally closed byra fracture plate, and adapted to be sent down the drill string to engage said assembly and close its fluid passage so as to be subjected to the full power of the circulation fluid pressure and be translated thereby to move said assembly to cutter expanding position, said fracture plate being .the pressure required to expand the reamer and to thereafter be fractured by a predetermined excess pressure to reestablish circulation through the expanded reamer, and being mounted in` the go-devil for removal therefrom and for replacement by a like fracture plate or by one having a greater or less fracture value.

3. In an `expansible reamer, the combination of: a tubular body adapted to be disposed above a drilling bit to constitute a portion of a rotary drill string conveying circulation fluid under pressure to said bit; a reaming cutter carried by said body, normally in collapsed position; al

cutter expanding assembly slidable in said body and having a fluid passage; and a go-devil having a longitudinal bore normally closed by a fracture plate, and adapted to' be sent down the drill string to engage said assembly and close its fluid passage so as to ybe subjected to the full power of the circulation uid pressure and be translated thereby to move said assembly to cutter expanding position, said fracture plate being of such thickness and strength as to withstand the pressure required to expand the reamer and to thereafter be fractured by a predetermined excess pressure to reestablish circulation through the expanded reamer, and said go-devil being formed of adjacent sections joined for separation at said fracture plate to permit it to be removed for replacement by a like fracture plate or by one having a greater or less fracture value.

4. In an expansible reamer, the combination of: a tubular body adapted to be disposed above a drilling bit to constitute a portion of a rotary drill string conveying circulation fluid under pressure to said bit; a roaming cutter carried by said body, normally in 'collapsed position; a cutter expanding piston slidable in said body and having a flow passage; means yieldingly maintaining said piston in its upper position; and a godevil adapted to be sent down the drill string to engage said piston and close its flow passage so as to be subjected to the full power of the circulating fluid pressure and be translated thereby to move the mandrel to cutter expanding position, said go-devil having a longitudinal bore and transverse ports connecting said bore with the space aboveV the' piston when the go-devil is in reamer operating position and being provided with a fracture member normally closing its bore above said ports, said fracture member being capable of withstandingrthe pressure required to operate the reamer and being adapted to be fractured by a predetermined excess pressure to open said bore, whereby the upper surface of the piston will be subjected to thefluid pressure to maintain the reamer in its expanded condition and circulation through the reamer will be reestablished.

5. In an expansible reamer, the 'combination of: a tubular body adapted to be disposed above a drilling bit to constitute a portion of a rotaryl drill string conveying circulation fluid under pressure to said bit and having one or more discharge ports discharging circulation fluid into the well bore above the reamer; a reaming cutter carried by said body; a cutter expanding assembly slidable in said body and having a iiow passage; and an elongated go-devil having a longitudinal bore normally closed by a fracture plate and adapted to be sent down the drill string to engage said assembly and at the same time extend upwardly into the bore of the drill string, said go-devil functioning as a sliding piston valve to close the flow passage of said assembly and to Shut off the circulation iiuid above the highest point of discharge of the drill string so as to be subjected to the full power of the circulation iiuid pressure and be translated thereby to drive the cutter expanding assembly to cutter expanding position, and said fracture plate being capable of withstanding the pressure required to expand the reamer and to be fractured by an excess pressure to open the lbore of the go-devil and reestablish circulation through the reamer to the drilling bit.

6. A go-devil for expanding a normally collapsed reamer disposed in a rotary drill string conveying circulation uid under pressure to said reamer and provided with a iiow passage, said go-devil being adapted to be sent down therdrill string and comprising a cylindrical member having a bore normally closed by a fracture plate and functioning as a slidable piston valve to close the drill string and be translated by the fluid pressure to expand the reamer, and said fracture plate being capable of withstanding the fluid pressure required to expand said reamer and of then being fractured by an excess pressure to reestablish circulation through the reamer.

'7. A go-devil for expanding a normally collapsed reamer disposed in a rotary vdrill string conveying circulation fluid under pressure to said reamer and provided with a flow passage, said go-devil being adapted to -be sent down the drill string and comprising a cylindrical member having a bore normally closed by a fracture plate and functioning as a slidable piston Valve to close the drill string and be translated by the fiuid pressure to expand the reamer, and said fracture plate being capable of withstanding the fluid pressure required to expand said reamer and of then being fractured by an excess pressure to reestablish circulation through the reamer, and being removably mounted in the go-devil for replacement by another fracture plate of the same fracture value or by one having a greater or less fracture value.

8. In a Well reaming tool adapted to be carried on a drill pipe, the combination comprising a body, an expansible cutter, and cutter expanding means comprising a go-deVil adapted to be dropped Within the drill pipe into said body and to be actuated by fluid pressure to 'cause expansion of the cutter, said go-devil having a uid passage therethrough and means normally closing said passage, the last mentioned means being responsive to fluid pressure applied to the go devil to open said passage.

9. In a well reaming tool adapted to be carried on a drill pipe, the combination comprising a body, an expansible cutter, and cutter expanding means comprising a tubular godevil adapted to be dropped Within the drill pipe into said body and to'be actuated by fluid pressure to cause expansion of the cutter, closure means carried by and normally closing the godevil bore, said closure means being displaceable by fluid pressure applied to the go-devil to open said bore.

10. A go-devil for expanding a normally collapsed reamer disposed in a rotary drill string conveying circulating fluid under pressure to said reamer and provided With a flow passage, said go-devil being adapted to be sent doWn the drill string and having a bore normally closed by a closure member and functioning as a piston to close said flow passage and be translated by the uid pressure to expand the reamer, and f` said closure member being capable of withstanding the fluid pressure required to expand said reamer and of then being displaceable by an eX- cess pressure to reestablish circulation through the reamer.

11. In an expansible reamer, the combination of a tubular body having a circulation passage therethrough, an expansible cutter carried by the body, a cutter expanding piston slidable in the body and subjectable to the pressure of circulation fluid flowing through the body; a go-deVil adapted to move down the circulation passage to engage the piston and close said passage, said go-devil having a longitudinal bore, pressure displaceable means normally closing said bore and capable of withstanding the pressure required to move the cutter expanding piston and adapted to be displaced by predetermined excess pres- .sure to open the bore, and a port in the go-devil adapted to transmit fluid pressure from its bore below the pressure displaceable means to the space above the piston.

JOHN GRANT. 

